Welcome on the homepage of the chair "Internet Technologies and Systems" of Prof. Dr. Christoph Meinel and his team. We like to inform you about our teaching and ongoing research activities in security, knowledge engineering, innovation and design thinking research.

The chair of Prof. Dr. Christoph Meinel offers courses in the following disciplines: Internet and Web Technologies, (Discrete) Mathematics and Logic, IT Security and Internet Security, Complexity Theory and Information Security as well as Design Thinking.

The research of the team of Prof. Dr. Christoph Meinel in the field of knowledge management and engineering focus on the challenging question, how to manage the mass of digital data, so-called "big data", from Internet and other sources in order to generate new knowledge.

More Lightweight, yet Stronger 802.15.4 Security through an Intra-Layer Optimization

802.15.4 security protects against the replay, injection, and eavesdropping of 802.15.4 frames. A core concept of 802.15.4 security is the use of frame counters for both nonce generation and anti-replay protection. While being functional, frame counters (i) cause an increased energy consumption as they incur a per-frame overhead of 4 bytes and (ii) only provide sequential freshness. The Last Bits (LB) optimization does reduce the per-frame overhead of frame counters, yet at the cost of an increased RAM consumption and occasional energy- and time-consuming resynchronization actions. Alternatively, the timeslotted channel hopping (TSCH) media access control (MAC) protocol of 802.15.4 avoids the drawbacks of frame counters by replacing them with timeslot indices, but findings of Yang et al. question the security of TSCH in general. In this paper, we assume the use of ContikiMAC, which is a popular asynchronous MAC protocol for 802.15.4 networks. Under this assumption, we propose an Intra-Layer Optimization for 802.15.4 Security (ILOS), which intertwines 802.15.4 security and ContikiMAC. In effect, ILOS reduces the security-related per-frame overhead even more than the LB optimization, as well as achieves strong freshness. Furthermore, unlike the LB optimization, ILOS neither incurs an increased RAM consumption nor requires resynchronization actions. Beyond that, ILOS integrates with and advances other security supplements to ContikiMAC. We implemented ILOS using OpenMotes and the Contiki operating system.